In order to practise the "I.L.B." technique, generally there is employed a ribbon in the form of a cinematographic film bearing a series of circuit units arranged in a longitudinal row to which the integrated circuits are to be respectively connected by soldering or welding the studs and the terminals. The film is driven in a stepwise manner past a welding post and the welding operation takes place by the application of a heated tool or welding tip to the studs and the respectively superposed terminals, the integrated circuit being, as may well be understood, maintained on a support normal to the welding tip.
Considering the extremely small dimensions of an integrated circuit, it is indispensable to obtain high precision alignment relative to the welding tip on the one hand and to the circuit unit to which it is to be connected on the other hand. In most cases, the misalignment must not exceed an error of 20 microns. In order to obtain such a high precision, it is usual to employ optical means such as a television circuit and to adjust the position of the integrated circuit relative to the circuit unit by means of the image captured by the camera, for example through manual displacement of the integrated circuit support along two perpendicular directions. Thus, this adjustment operation may only be obtained if the field of the camera in the welding post is disengaged, which requires lateral displacement of the welding tip before and after the alignment during each working cycle.
Moreover, the working cycle comprises a loading operation for the integrated circuit and one may thus arrive at a working cycle of 4 seconds per integrated circuit of which one second is required for the displacement of the welding tip into and out of the camera field of vision.
The invention has as its purpose to provide a process and apparatus for practising the technique of "I.L.B." coupling the required welding precision to a working rhythm clearly greater than that which has been obtained up to the present using this technique.